JP7170966B2 - vehicle drive - Google Patents

Description

TECHNICAL FIELD The present invention relates to a vehicle drive system, and more particularly to a vehicle drive system that uses an internal combustion engine to drive a vehicle.

Japanese Patent Laying-Open No. 2003-287088 (Patent Document 1) describes an automatic transmission. This automatic transmission is based on a gear-type manual transmission and has an automated shift operation, and the shift operation and select operation of the gear stage during gear shifting are automatically performed by an actuator. Further, in such an automatic transmission, it is possible to set a manual mode in which the driver selects a desired gear and the actuator shifts to the selected gear.

Japanese Unexamined Patent Application Publication No. 2003-287088

However, in an automatic transmission that automates gear shifting operations based on a gear-type manual transmission, such as that described in Patent Document 1, it is inevitable that the driving force transmitted during gear shifting is interrupted. There's a problem. That is, when the driving force is interrupted due to gear shifting while the vehicle is accelerating, the acceleration temporarily decreases, giving the occupant a "stall feeling" and degrading the ride comfort of the vehicle. In addition, when the vehicle decelerates and the internal combustion engine is acting as a brake, the acceleration momentarily increases when gear shifting is performed, giving the occupants a feeling of idling, which deteriorates the ride comfort of the vehicle. There is a problem that

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a vehicle drive system capable of suppressing the "feeling of stalling" and "feeling of idling" given to the occupant at the time of shifting in a vehicle using a stepped transmission, thereby improving the ride comfort. It is an object.

In order to solve the above-described problems, the present invention provides a vehicle drive system that uses an internal combustion engine to drive a vehicle, comprising: an internal combustion engine that generates driving force for driving main drive wheels of the vehicle; A stepped transmission that is connected to the output shaft of an internal combustion engine and converts the rotation speed of the output shaft of the internal combustion engine and outputs it, and a main drive that applies driving force to the auxiliary drive wheels or does not go through the stepped transmission It has an assist motor provided to apply a driving force to the wheels and a motor control device for controlling the driving force output by the assist motor, and the stepped transmission transmits the driving force when shifting to the low speed side. Although the driving force is interrupted, it is a seamless shift type transmission that does not substantially interrupt the driving force when shifting to the high speed side. It is characterized by generating power and supplementing the interruption of driving force during gear shifting.

In the present invention constructed as described above, the internal combustion engine generates a driving force for driving the main driving wheels of the vehicle, and the stepped transmission converts the rotation speed of the output shaft of the internal combustion engine and outputs the output. This stepped transmission is a seamless shift type transmission in which the driving force to be transmitted is interrupted when shifting to the low speed side, but substantially no driving force is interrupted when shifting to the high speed side. On the other hand, the assist motor is provided so as to apply a driving force to the sub-driving wheels or to apply a driving force to the main driving wheels without the stepped transmission. control power. In addition, the motor control device causes the assist motor to generate driving force when shifting to the low speed side by means of the stepped transmission, and compensates for interruption of the driving force during shifting.

According to the present invention configured as described above, the motor control device causes the assist motor to generate a driving force to compensate for the discontinuity of the driving force at the time of shifting, thereby suppressing the "stall feeling" given to the occupant. It is possible to improve the ride comfort of the vehicle. Here, a dual clutch transmission (DCT) is known as a stepped transmission in which the driving force is not substantially interrupted during shifting. However, since this DCT has a structure in which two sets of torque transmission systems are switched by two clutches, the mechanism is complicated and the weight is large. For this reason, if a DCT is used as a transmission, the weight of the DCT reduces the dynamic performance (acceleration performance, cornering performance, etc.) of the vehicle and increases the cost.

Further, by using a motor in combination with a general stepped transmission in which the driving force is interrupted during gear shifting, it is conceivable to supplement the interruption of the driving force during gear shifting with the driving force of the motor. However, in order to supplement the discontinuity of driving force that occurs in a general stepped transmission with a motor, a high-output motor capable of generating a large momentary torque is required. A problem arises that the cost increases.

On the other hand, the seamless shift type stepped transmission described in Japanese Patent No. 5707119 can be constructed relatively light and substantially eliminates the interruption of the driving force at the time of shifting. can be done. Here, in the seamless shift type stepped transmission described in the publication, etc., it is possible to substantially eliminate the interruption of the driving force at the time of shifting to the low speed side or to the high speed side. However, it is very difficult to manufacture a seamless shift type transmission capable of eliminating interruptions in driving force during both low-speed and high-speed shifting.

Faced with such a problem, the inventors of the present invention have found that, in general running conditions of a vehicle, a torque that is large enough to compensate for the discontinuity of the driving force that occurs when switching the stepped transmission to the high speed side (shifting up). is required, but it has been found that switching to the low speed side (shift down) can be supplemented with a relatively small driving force. Therefore, the inventor of the present invention proposed a seamless shift type transmission that does not substantially interrupt the driving force when shifting to the high speed side, and a relatively small assist motor that supplements the interruption of the driving force when shifting to the low speed side. I thought of combining them. As a result, it is possible to improve the ride comfort of the vehicle by suppressing interruptions in driving force during gear shifting, while avoiding a significant increase in vehicle weight and cost. became.

In the present invention, preferably, the vehicle body further includes a main drive motor that generates drive force for the main drive wheels, and the motor control device uses the drive force generated by the main drive motor and the assist motor. In the electric motor running mode, the motor control device causes the assist motor to generate driving force only when the vehicle is accelerated at a predetermined vehicle speed or higher.

According to the present invention configured as described above, since the main drive motor that generates the drive force for the main drive wheels is provided, the electric motor drive mode that does not use the drive force of the internal combustion engine can be realized. As a result, the vehicle can be driven even in areas where vehicle driving by the internal combustion engine is restricted. In addition, since the assist motor generates driving force when the vehicle is accelerated at a predetermined speed or higher, the electric motor driving mode can be realized with a small-sized main driving motor, and the weight of the vehicle as a whole can be reduced.

In the present invention, the assist motor is preferably an in-wheel motor provided on the main drive wheels or the sub drive wheels.
According to the present invention configured as described above, since the assist motor is an in-wheel motor, the generated driving force is directly transmitted to the wheels, so that the driving force is instantaneously added to the vehicle at the timing when the driving force is interrupted. be able to. Therefore, it is possible to more effectively suppress the sense of stall given to the occupant due to the interruption of the driving force.

In the present invention, preferably, the assist motor is provided so as to directly drive the auxiliary drive wheels without having its output changed.
According to the present invention configured as described above, the auxiliary drive wheels are directly driven without changing the speed of the output of the assist motor, so there is no need to provide a mechanism for changing the speed of the rotational output of the assist motor. , the vehicle can be made lighter.

In the present invention, the motor control device is preferably configured to be capable of executing an internal combustion engine running mode in which the vehicle runs by driving force generated by the internal combustion engine, and the motor control device controls the main drive motor in the internal combustion engine running mode. Do not generate driving force by

According to the present invention configured as described above, in the internal combustion engine running mode, since no driving force is generated by the main drive motor, the vehicle is driven by the driving force generated by the internal combustion engine, and the driver runs with the internal combustion engine. You can fully enjoy the driving feeling of the vehicle.

The present invention preferably further includes a power transmission mechanism for transmitting the driving force generated by the internal combustion engine, the internal combustion engine is arranged in the front part of the vehicle, and the driving force generated by the internal combustion engine is transmitted to the power transmission mechanism. is transmitted to the rear wheels, which are the main drive wheels.

According to the present invention configured as described above, the driving force generated by the internal combustion engine arranged in the front part of the vehicle is transmitted to the rear wheels, and the rear wheels are driven, so that the dynamic performance of the vehicle can be improved. can.

According to the vehicle drive system of the present invention, in a vehicle using a stepped transmission, it is possible to suppress the "stall feeling" and "idle running feeling" given to the occupant at the time of shifting, and improve the ride comfort.

1 is a layout diagram of a vehicle equipped with a vehicle drive system according to a first embodiment of the present invention; FIG. 1 is a block diagram showing a power supply configuration of a vehicle drive system according to a first embodiment of the invention; FIG. FIG. 4 is a diagram schematically showing an example of voltage change when electric power is regenerated in a capacitor in the vehicle drive system according to the first embodiment of the present invention; FIG. 3 is a diagram showing the relationship between the output of each motor and the vehicle speed used in the vehicle drive system according to the first embodiment of the present invention; 2 is a cross-sectional view schematically showing the structure of a sub-drive motor used in the vehicle drive system according to the first embodiment of the invention; FIG. FIG. 3 is a cross-sectional view for schematically explaining the principle of operation of the transmission provided in the vehicle drive system of the first embodiment of the invention; 4 is a time chart showing an example of operations in an electric motor running mode and an internal combustion engine running mode executed by the control device in the vehicle drive system according to the first embodiment of the present invention; 4 is a graph schematically showing the acceleration of the vehicle when the transmission is shifted up in the vehicle drive system according to the first embodiment of the present invention; 4 is a graph schematically showing the acceleration of the vehicle when the transmission is downshifted in the vehicle drive system according to the first embodiment of the present invention; 4 is a graph schematically showing the acceleration of the vehicle when the transmission is downshifted in the vehicle drive system according to the first embodiment of the present invention; FIG. 7 is a layout diagram of a vehicle equipped with a vehicle drive system according to a second embodiment of the present invention;

Preferred embodiments of the present invention will now be described with reference to the accompanying drawings.
FIG. 1 is a layout diagram of a vehicle equipped with a vehicle drive system according to a first embodiment of the present invention.

As shown in FIG. 1, a vehicle 1 equipped with a vehicle drive system according to the first embodiment of the present invention has an engine 12, which is an internal combustion engine, mounted in front of the driver's seat and in front of the vehicle. This is a so-called FR (Front engine, Rear drive) vehicle that drives a pair of left and right rear wheels 2a. As will be described later, the rear wheels 2a are also driven by a main drive motor, and the pair of left and right front wheels 2b, which are sub-drive motors, are driven by a sub-drive motor.

A vehicle drive system 10 according to an embodiment of the present invention mounted on a vehicle 1 includes an engine 12 that drives rear wheels 2a, a power transmission mechanism 14 that transmits driving force to the rear wheels 2a, and a main body that drives the rear wheels 2a. It has a drive motor 16, a battery 18 that is a capacitor, a sub-drive motor 20 that is an assist motor that drives the front wheels 2b, a capacitor 22, and a control device 24 that is a motor control device.

The engine 12 is an internal combustion engine for generating driving force for the rear wheels 2a, which are the main driving wheels of the vehicle 1. As shown in FIG. In this embodiment, an in-line four-cylinder engine is employed as the engine 12, and the engine 12 arranged at the front of the vehicle 1 drives the rear wheels 2a through the power transmission mechanism 14. As shown in FIG.

The power transmission mechanism 14 is configured to transmit the driving force generated by the engine 12 to the rear wheels 2a, which are the main drive wheels. The power transmission mechanism 14 includes a propeller shaft 14a connected to the engine 12, a clutch 14b, and a transmission 15 that is a stepped transmission. The propeller shaft 14 a extends rearward of the vehicle 1 through a propeller shaft tunnel (not shown) from the engine 12 arranged at the front of the vehicle 1 . A rear end of the propeller shaft 14a is connected to a transmission 15 via a clutch 14b. An output shaft of the transmission 15 is connected to an axle (not shown) of the rear wheel 2a to drive the rear wheel 2a.

In this embodiment, as the transmission 15, a seamless shift type transmission is employed in which the driving force to be transmitted is interrupted when shifting to the low speed side, but substantially the driving force is not interrupted when shifting to the high speed side. there is Further, in the present embodiment, the transmission 15 has a so-called transaxle arrangement. As a result, the main body of the transmission with a large outer diameter does not exist immediately after the engine 12, so the width of the floor tunnel (propeller shaft tunnel) can be reduced, and the passenger's central side foot space can be secured. It is possible to make the occupant take a bilaterally symmetric lower body posture facing the front. Furthermore, it becomes easy to make the outer diameter and length of the main drive motor 16 large enough according to the output while ensuring the posture of the passenger. Details of the transmission 15 will be described later.

The main drive motor 16 is an electric motor for generating driving force for the main drive wheels, and is arranged adjacent to the engine 12 on the rear side of the engine 12 . An inverter (INV) 16 a is arranged adjacent to the main drive motor 16 , and this inverter 16 a converts the current from the battery 18 into alternating current and supplies it to the main drive motor 16 . Further, the main drive motor 16 is connected in series with the engine 12, and the driving force generated by the main drive motor 16 is also transmitted to the rear wheels 2a via the power transmission mechanism 14. Alternatively, the present invention can be constructed such that the main drive motor 16 is connected to the middle of the power transmission mechanism 14 and the driving force is transmitted to the rear wheels 2a through a part of the power transmission mechanism 14. In this embodiment, a 25 kW permanent magnet motor (permanent magnet synchronous motor) driven at 48 V is employed as the main drive motor 16 .

Battery 18 is primarily a reservoir for storing power to operate main drive motor 16 . Also, in this embodiment, the battery 18 is housed in a propeller shaft tunnel (not shown). Furthermore, in this embodiment, a 48 V, 3.5 kWh lithium ion battery (LIB) is used as the battery 18 .
As described above, since the transaxle arrangement is adopted in the present embodiment, the space in front of the floor tunnel (propeller shaft tunnel) created by this arrangement must be expanded to accommodate the battery 18. can be done. As a result, the capacity of the battery 18 can be secured and expanded without narrowing the space on the central side of the occupant by increasing the width of the floor tunnel.

The sub-driving motor 20 is provided for each front wheel 2b under the spring of the vehicle 1 so as to generate a driving force for the front wheel 2b, which is a sub-driving wheel. In this embodiment, each wheel of the front wheels 2b is supported by a double wishbone type suspension, and suspended by an upper arm, a lower arm, a spring, and a shock absorber (not shown). The sub-drive motors 20 are in-wheel motors and housed in the wheels of the front wheels 2b. Therefore, the sub-drive motors 20 are arranged so-called "unsprung" of the vehicle 1 to drive the front wheels 2b respectively. Further, as shown in FIG. 1, each auxiliary drive motor 20 is supplied with a current from a capacitor (CAP) 22 which is converted into an alternating current by each inverter 20a. Furthermore, in this embodiment, the sub-driving motor 20 is not provided with a reduction gear, and the driving force of the sub-driving motor 20 is directly transmitted to the front wheels 2b. Further, in this embodiment, a 17 kW induction motor is employed as each sub-driving motor 20 .

A capacitor (CAP) 22 is provided to store power regenerated by the sub-drive motor 20 . Also, the capacitor 22 is arranged immediately before the engine 12 and supplies electric power to the auxiliary drive motors 20 provided for the front wheels 2 b of the vehicle 1 . Furthermore, the capacitor 22 is configured to accumulate electric charge with a voltage higher than that of the battery 18, and is arranged in a region between the left and right front wheels 2b, which are auxiliary drive wheels. The sub-drive motor 20 driven primarily by the power stored in the capacitor 22 is driven at a voltage higher than that of the main drive motor 16 .

The control device 24 is configured to control the engine 12, the main drive motor 16, and the sub-drive motor 20 to execute the electric motor drive mode and the internal combustion engine drive mode. In addition, the control device 24 is configured to control the transmission 15 to change the gear stage, and to control the sub-drive motor 20 to compensate for interruptions in the driving force associated with gear shifting. Specifically, the control device 24 can be composed of a microprocessor, a memory, an interface circuit, and a program (not shown) for operating them. The details of the control by the control device 24 will be described later.

Also, as shown in FIG. 1, a high-voltage DC/DC converter 26a and a low-voltage DC/DC converter 26b, which are voltage converters, are arranged near the capacitor 22, respectively. These high-voltage DC/DC converter 26a, low-voltage DC/DC converter 26b, capacitor 22, and two inverters 20a are unitized to form an integrated unit.

Next, the power source configuration of the vehicle drive system 10 according to the first embodiment of the present invention and the driving of the vehicle 1 by each motor will be described with reference to FIGS. 2 to 4. FIG.
FIG. 2 is a block diagram showing the power supply configuration of the vehicle drive system 10 according to the first embodiment of the invention. FIG. 3 is a diagram schematically showing an example of voltage changes when electric power is regenerated in the capacitor 22 in the vehicle drive device 10 of the present embodiment. FIG. 4 is a diagram showing the relationship between the output of each motor used in the vehicle drive system 10 of this embodiment and the vehicle speed.

First, the power supply configuration of the vehicle drive system 10 according to the embodiment of the present invention will be described. As shown in FIG. 2, the battery 18 and the capacitor 22 provided in the vehicle drive system 10 are connected in series. The main drive motor 16 is driven by about 48V, which is the reference output voltage of the battery 18, and the subdrive motor 20 is driven by the sum of the output voltage of the battery 18 and the voltage across the terminals of the capacitor 22. is driven by a voltage of Therefore, the sub-drive motor 20 is always driven by power supplied via the capacitor 22 .

An inverter 16a is attached to the main drive motor 16, and after converting the output of the battery 18 into an alternating current, the main drive motor 16, which is a permanent magnet motor, is driven. Similarly, an inverter 20a is attached to each sub-drive motor 20, and the sub-drive motor 20, which is an induction motor, is driven after converting the output of the battery 18 and the capacitor 22 into alternating current. Since the sub-drive motor 20 is driven at a voltage higher than that of the main drive motor 16, a harness (not shown) that supplies power to the sub-drive motor 20 is required to have high insulation. However, since the capacitors 22 are arranged close to each sub-drive motor 20, it is possible to minimize the increase in weight due to the high insulation of the harness.

Further, when the vehicle 1 decelerates or the like, the main drive motor 16 and the sub-drive motors 20 function as generators to regenerate the kinetic energy of the vehicle 1 to generate electric power. Electric power regenerated by the main drive motor 16 is stored in the battery 18 , and electric power regenerated by each sub-drive motor 20 is mainly stored in the capacitor 22 .

A high-voltage DC/DC converter 26a, which is a voltage converter, is connected between the battery 18 and the capacitor 22, and the high-voltage DC/DC converter 26a operates when the charge accumulated in the capacitor 22 is insufficient ( When the voltage across the terminals of the capacitor 22 drops), the voltage of the battery 18 is boosted and the capacitor 22 is charged. On the other hand, when the voltage across the terminals of the capacitor 22 rises above a predetermined voltage due to the regeneration of energy by each sub-drive motor 20, the charge accumulated in the capacitor 22 is stepped down and applied to the battery 18. charge the battery. That is, after the electric power regenerated by the sub-drive motor 20 is stored in the capacitor 22, part of the stored charge is charged to the battery 18 via the high-voltage DC/DC converter 26a.

Furthermore, a low-voltage DC/DC converter 26b is connected between the battery 18 and the 12V electrical equipment of the vehicle 1 . Since the control device 24 of the vehicle driving device 10 and many of the electrical components of the vehicle 1 operate at a voltage of 12 V, the charge accumulated in the battery 18 is stepped down to 12 V by the low-voltage DC/DC converter 26b, and these devices are operated. supply to

Next, referring to FIG. 3, charging and discharging of capacitor 22 will be described.
As shown in FIG. 3, the voltage across capacitor 22 is the sum of the base voltage from battery 18 and the voltage across capacitor 22 itself. During deceleration of the vehicle 1 , electric power is regenerated by each auxiliary drive motor 20 and the regenerated electric power is charged in the capacitor 22 . When the capacitor 22 is charged, the terminal voltage rises relatively rapidly. When the voltage of capacitor 22 rises above a predetermined voltage due to charging, the voltage of capacitor 22 is lowered by high-voltage DC/DC converter 26a, and battery 18 is charged. As shown in FIG. 3, the charging of the battery 18 from the capacitor 22 is performed relatively slowly than the charging of the capacitor 22, and the voltage of the capacitor 22 is relatively slowly lowered to the proper voltage.

That is, the electric power regenerated by each sub-drive motor 20 is temporarily stored in the capacitor 22, and then slowly charged to the battery 18. FIG. Depending on the period during which the regeneration is performed, the regeneration of electric power by each sub-drive motor 20 and the charging of the battery 18 from the capacitor 22 may overlap.
On the other hand, the power regenerated by the main drive motor 16 is directly charged to the battery 18 .

Next, the relationship between the vehicle speed and the output of each motor in the vehicle drive system 10 according to the embodiment of the present invention will be described with reference to FIG. FIG. 4 is a graph showing the relationship between the speed of the vehicle 1 and the output of each motor at each speed in the vehicle drive system 10 of this embodiment. In FIG. 4, the output of the main drive motor 16 is indicated by a dashed line, the output of one sub-drive motor 20 is indicated by a dashed line, the total output of the two sub-drive motors 20 is indicated by a two-dot chain line, and the output of all motors. The total is indicated by a solid line.

In this embodiment, a permanent magnet motor is used for the main drive motor 16. Therefore, as shown by the dashed line in FIG. As the speed increases, the motor output that can be output decreases. That is, in the present embodiment, the main drive motor 16 is driven at about 48 V and outputs a maximum torque of about 200 Nm up to about 1000 rpm, and the torque decreases as the rotation speed increases above about 1000 rpm. Further, in this embodiment, the main drive motor 16 is configured to obtain a continuous output of about 20 kW in the lowest speed range and a maximum output of about 25 kW.

On the other hand, since the sub-drive motor 20 employs an induction motor, the output of the sub-drive motor 20 is extremely small in the low vehicle speed range, as indicated by the one-dot chain line and the two-dot chain line in FIG. As the speed increases, the output increases, and after the maximum output is obtained at a vehicle speed of about 130 km/h, the motor output decreases. In this embodiment, the sub-drive motor 20 is driven at about 120 V and is configured to obtain an output of about 17 kW per unit and a total output of about 34 kW at a vehicle speed of about 130 km/h. That is, in this embodiment, the auxiliary drive motor 20 has a peak torque curve at about 600 to 800 rpm, and a maximum torque of about 200 Nm is obtained.

A solid line in FIG. 4 indicates the total output of the main drive motor 16 and the two sub-drive motors 20 . As is clear from this graph, in this embodiment, a maximum output of about 53 kW is obtained at a vehicle speed of about 130 km/h, and this maximum output at this vehicle speed satisfies the driving conditions required in the WLTP test. be able to. In the solid line in FIG. 4, the output values of the two sub-driving motors 20 are added even in the low vehicle speed range. never That is, the vehicle is driven only by the main drive motor 16 when starting and in a low vehicle speed range, and only when a large output is required in a high vehicle speed range (such as when accelerating the vehicle 1 in a high vehicle speed range). A secondary drive motor 20 generates an output. In this way, by using the induction motor (sub-drive motor 20) capable of generating a large output in the high rotation region only in the high speed region, the increase in vehicle weight can be suppressed when necessary (at a predetermined speed or higher). (e.g., when accelerating at high speed).

Next, referring to FIG. 5, the configuration of the auxiliary drive motor 20 employed in the vehicle drive system 10 of the embodiment of the invention will be described. FIG. 5 is a cross-sectional view schematically showing the structure of the sub-drive motor 20. As shown in FIG.
As shown in FIG. 5, the sub-drive motor 20 is an outer rotor type induction motor composed of a stator 28 and a rotor 30 rotating around the stator.

The stator 28 has a generally disc-shaped stator base 28a, a stator shaft 28b extending from the center of the stator base 28a, and a stator coil 28c attached around the stator shaft 28b. The stator coil 28c is housed in an electrical insulating liquid chamber 32, and is immersed in an electrical insulating liquid 32a filled therein, thereby boiling and cooling.

The rotor 30 is configured in a generally cylindrical shape so as to surround the stator 28, and includes a rotor body 30a configured in a generally cylindrical shape with one end closed, and a rotor disposed on the inner peripheral wall surface of the rotor body 30a. and a coil 30b. The rotor coil 30b is arranged to face the stator coil 28c so that an induced current is generated by the rotating magnetic field generated by the stator coil 28c. Also, the rotor 30 is supported by a bearing 34 attached to the tip of the stator shaft 28b so as to rotate smoothly around the stator 28. As shown in FIG.

The stator base 28 a is supported by an upper arm and a lower arm (not shown) that suspend the front wheels of the vehicle 1 . On the other hand, the rotor body 30a is directly fixed to a wheel (not shown) of the front wheel 2b. The alternating current converted to alternating current by the inverter 20a is supplied to the stator coil 28c to generate a rotating magnetic field. This rotating magnetic field causes an induced current to flow in the rotor coil 30b, generating a driving force for rotating the rotor body 30a. Thus, the driving force generated by each sub-driving motor 20 directly drives the wheel (not shown) of each front wheel 2b to rotate.

Next, the configuration of the transmission 15 will be described with reference to FIG.
FIG. 6 is a cross-sectional view for schematically explaining the operating principle of the transmission 15, which is a stepped transmission provided in the vehicle drive system 10 of the first embodiment of the invention. In this embodiment, the transmission 15 employed in the vehicle drive system 10 is a 6-speed stepped transmission. The mechanism and action will be exemplified. In addition, shifting from the low speed side to the high speed side can be realized by the same configuration between any gears.

As shown in FIG. 6, the transmission 15 includes a main shaft 36 connected to the output shaft of the engine 12, a counter shaft 38 that is the output shaft of the transmission 15, a low speed side gear 40 (for example, 1st gear), and a high-speed gear 42 (for example, a second gear) having a gear ratio smaller than that of the low-speed gear 40 . Further, the transmission 15 includes a low-speed side dog clutch 44 provided on the main shaft 36, a high-speed side dog clutch 46, a shift fork 48 for operating the dog clutch 44, and a dog clutch 46. and a shift fork 50 for operating the .

The main shaft 36 is an input shaft of the transmission 15 , is rotatably supported by a transmission case (not shown), and is connected to an output shaft of the engine 12 . In this embodiment, the main shaft 36 is connected to the output shaft of the engine 12 via the propeller shaft 14a, but the output shaft of the engine 12 and the main shaft 36 may be directly connected.

The countershaft 38 is an output shaft of the transmission 15 and is rotatably supported with respect to a transmission case (not shown). The rotation of the countershaft 38 is transmitted to a differential gear (not shown) arranged at the rear portion of the vehicle 1 to drive the rear wheels 2a, which are the main drive wheels.

The low-speed side gear 40 is composed of a gear 40a attached to the main shaft 36 and a gear 40b attached to the countershaft 38. These gears 40a and 40b are always in mesh. The gear 40b of the countershaft 38 is fixed with respect to the countershaft 38 and configured to rotate together with the countershaft 38 at all times. On the other hand, the gear 40a of the main shaft 36 is attached to the main shaft 36 so as to be free to move (however, it does not slide in the axial direction). As a result, the gear 40 a can transmit power while being fixed to the main shaft 36 by the dog clutch 44 .

Similarly, the high-speed side gear 42 is composed of a gear 42a attached to the main shaft 36 and a gear 42b attached to the countershaft 38, and these gears 42a and 42b are in constant mesh. The gear 42b of the countershaft 38 is fixed with respect to the countershaft 38 and configured to rotate together with the countershaft 38 at all times. On the other hand, the gear 42a of the main shaft 36 is attached to the main shaft 36 so as to be free to move, and is configured to be able to transmit power while being fixed to the main shaft 36 by the dog clutch 46. ing.

The low speed dog clutch 44 has a clutch cam ring 52 fixed to the main shaft 36 and a clutch ring 54 attached to the outer periphery of the clutch cam ring 52 .
The clutch cam ring 52 is a cylindrical member attached to the outer circumference of the main shaft 36 and configured to rotate integrally with the main shaft 36 . A plurality of V-shaped cam grooves 52a extending in the axial direction are provided on the outer peripheral surface of the clutch cam ring 52 at equal intervals in the circumferential direction.

The clutch ring 54 is a doughnut-shaped disk arranged on the outer periphery of the clutch cam ring 52 and attached to the clutch cam ring 52 so as to be slidable in the axial direction. In addition, a plurality of cam protrusions 54a having a circular cross-section are provided on the inner periphery of the clutch ring 54 at equal intervals in the circumferential direction and protrude radially inward. These cam protrusions 54a are received in a plurality of cam grooves 52a provided on the outer circumference of the clutch cam ring 52, respectively. With this configuration, the clutch ring 54 is also moved circumferentially along the V-shaped cam groove 52a provided in the clutch cam ring 52 when the clutch ring 54 is slid in the axial direction.

On the other hand, one surface of the clutch ring 54 is provided with a plurality of clutch teeth 54b so as to protrude in the axial direction. These clutch teeth 54b are formed on the surface of the clutch ring 54 facing the gear 40a at equal intervals so as to extend radially. On the other hand, the surface of the gear 40a facing the clutch ring 54 is also formed with a plurality of clutch teeth 40c at regular intervals so as to extend radially. Each clutch tooth 40c of gear 40a and each clutch tooth 54b of clutch ring 54 are formed to engage with each other when clutch ring 54 is axially slid toward gear 40a. . When the clutch teeth 40c and 54b are thus engaged with each other, the gear 40a is prevented from rotating with respect to the main shaft 36, and power can be transmitted by the low-speed side gear 40 (gears 40a and 40b). 6 shows a state in which clutch ring 54 has been slid to a position close to gear 40a and clutch teeth 40c and 54b are engaged.

Furthermore, the outer peripheral edge of the clutch ring 54 is received in a recess 48 a provided at the tip of the shift fork 48 . Therefore, the movement of the shift fork 48 axially slides the clutch ring 54 on the clutch cam ring 52 to switch between engagement and disengagement of the clutch ring 54 and the gear 40a.

Next, the high-speed side dog clutch 46 has the same configuration as the low-speed side dog clutch 44, and includes a clutch cam ring 56 fixed to the main shaft 36 and a clutch cam ring 56 that is fixed to the main shaft 36. and a clutch ring 58 mounted on the outer periphery of the .
The clutch cam ring 56 is a cylindrical member, and a plurality of V-shaped cam grooves 56a extending substantially in the axial direction are provided on its outer peripheral surface at equal intervals in the circumferential direction.

The clutch ring 58 is a doughnut-shaped disc arranged on the outer periphery of the clutch cam ring 52, and on the inner periphery thereof, a plurality of cam protrusions 58a having a circular cross-section projecting radially inward. are provided at equal intervals in the circumferential direction. These cam protrusions 58a are respectively received in cam grooves 56a on the outer periphery of the clutch cam ring 56, and the clutch ring 58 slides along the V-shaped cam grooves 56a when axially slid. It is also moved in the circumferential direction.

On the other hand, one surface of the clutch ring 58 is provided with a plurality of clutch teeth 58b so as to protrude in the axial direction. On the other hand, the surface of the gear 42a facing the clutch ring 58 is also formed with a plurality of clutch teeth 40c at regular intervals so as to extend radially. Each clutch tooth 42c of the gear 42a and each clutch tooth 58b of the clutch ring 58 are formed so as to engage with each other. Power can be transmitted by 42 (gears 42a and 42b). 6 shows a state in which the clutch ring 58 is slid away from the gear 42a and the clutch teeth 42c and 58b are disengaged.

Furthermore, the outer peripheral edge of the clutch ring 58 is received in a recess 50 a provided at the tip of the shift fork 50 . Therefore, the movement of the shift fork 50 axially slides the clutch ring 58 on the clutch cam ring 54 to switch between engagement and disengagement of the clutch ring 58 and the gear 42a. That is, as the shift forks 48 and 50 move, the engagement and disengagement of the clutch ring 54 and the gear 40a and between the clutch ring 58 and the gear 42a are switched respectively. As a result, power transmission by the low speed side gear 40 (gears 40a and 40b) and power transmission by the high speed side gear 42 (gears 42a and 42b) are switched.

Further, the shift forks 48, 50 are moved along a groove (not shown) provided on the outer peripheral surface of a cylindrical shift drum (not shown) in the axial direction of the main shaft 36 (horizontal direction in FIG. 6). is provided so as to be able to move to Accordingly, when the shift drum (not shown) is rotated by the actuator (not shown), the shift forks 48 and 50 are moved in a predetermined pattern according to the grooves (not shown) formed in the shift drum. Gear engagement is switched.

Next, switching of gears in the transmission 15 will be described.
Shifting by the transmission 15 is automatically effected by the controller 24 controlling actuators (not shown) to rotate a shift drum (not shown) and move each shift fork. Further, the gear set by the control device 24 is automatically selected based on the number of revolutions of the engine 12, the speed of the vehicle 1, etc. (automatic mode), or is selected based on the driver's operation (manual mode). mode).

As described above, FIG. 6 shows a state in which power is transmitted by the low-speed gear 40 and the gear 42 a of the high-speed gear 42 is rotating idle with respect to the main shaft 36 . When switching (shifting up) from the state in which power is transmitted by the low-speed gear 40 shown in FIG. move the shift forks 48, 50 along. That is, when switching the transmission 15 to the high speed side, the shift fork 48 is moved away from the gear 40a and the shift fork 50 is brought closer to the gear 42a.

First, while power is being transmitted by the low-speed gear 40, the clutch teeth 54b of the clutch ring 54 and the clutch teeth 40c of the gear 40a are engaged. In this state, the main shaft 36, gear 40a, clutch cam ring 52 and clutch ring 54 are integrally rotating at exactly the same number of revolutions. Next, in order to switch the transmission 15 to the high speed side, the shift fork 50 moves the clutch ring 58 on the high speed side closer to the gear 42a. As a result, the clutch teeth 58b of the clutch ring 58 and the clutch teeth 42c of the gear 42a come into contact with each other, and the power is instantaneously transmitted by the high-speed side gear 42 as well. Rotational speed changes slightly.

This change in rotational speed causes a slight rotational speed difference between the perfectly matched clutch cam ring 52 and clutch ring 54 rotations. Based on this rotational speed difference, the slope of the V-shaped cam groove 52a formed in the clutch cam ring 52 presses the cam protrusion 54a of the clutch ring 54. As shown in FIG. The force component of the force with which the slope of the cam groove 52a presses the cam protrusion 54a disengages the clutch teeth 54b and 40c and acts in the direction of separating the clutch ring 54 from the gear 40a. 54 is disengaged from gear 40a. On the other hand, the clutch teeth 58b of the clutch ring 58 on the high speed side and the clutch teeth 42c of the gear 42a are engaged, and power is transmitted by the gear 42 on the high speed side.

Thus, disengagement of clutch ring 54 and gear 40a based on movement of shift fork 48 and engagement of clutch ring 58 and gear 42a based on movement of shift fork 50 are performed substantially simultaneously. . As a result, the shift from the low-speed gear 40 to the high-speed gear 42 is instantaneously executed, and the shift to the high-speed side is completed without substantial interruption of the driving force.

In FIG. 6, gears to be engaged are arranged only on one side of each clutch ring, but clutch teeth are provided on both sides of each clutch ring, and both sides of each clutch ring are selectively engaged. The transmission can also be configured so that the gears to be engaged are arranged. As a result, a large number of gear stages can be provided with a compact configuration.

Next, with reference to FIG. 7, operations in the electric motor driving mode and the internal combustion engine driving mode executed by the control device 24 will be described. FIG. 7 is a time chart showing an example of operation in each mode.

The time chart shown in FIG. 7 shows, from the top, the speed of the vehicle 1, the torque generated by the engine 12, the torque generated by the main drive motor 16, the torque generated by the auxiliary drive motor 20, the voltage of the capacitor 22, and the current of the capacitor 22. , and battery 18 current. In the graph showing the torque of the main drive motor 16 and the torque of the auxiliary drive motor 20, a positive value means that each motor is generating torque, and a negative value means that each motor is generating torque. It means the state of regenerating energy. In the graphs showing the current of the capacitor 22 and the current of the battery 18, a negative value means that power is supplied (discharged) to each motor, and a positive value means that the power regenerated in each motor is charged. means that the

First, at time t1 in FIG. 7, the driver starts and accelerates the vehicle ₁ in the electric motor running mode. In this state, the main drive motor 16 generates torque and the vehicle speed increases (time t ₁ to t ₂ in FIG. 10). At this time, while a discharge current flows from the battery 18 that supplies power to the main drive motor 16, the auxiliary drive motor 20 does not generate torque, so the discharge current from the capacitor 22 remains zero and the voltage of the capacitor 22 It does not change. Further, from time t ₁ to t ₂ , the engine 12 is not driven (no fuel is supplied to the engine 12 and no torque is generated) because the electric motor running mode is set.

In the example shown in FIG. 7, after accelerating the vehicle 1 between times t ₁ and t ₂ , the vehicle 1 runs at a constant speed until time t ₃ . Next, at time t3 _, when the driver operates the brake pedal (not shown) of the vehicle 1, the driving by the main driving motor 16 is stopped (torque is not generated), and the auxiliary driving motor 20 causes the vehicle to The kinetic energy of 1 is regenerated as electric power. The regeneration of kinetic energy slows down the vehicle 1, and the discharge current from the battery 18 becomes zero.

At time t4 in FIG. ₇ , when the vehicle 1 stops, the charging current to the capacitor 22 becomes zero and the voltage of the capacitor 22 also becomes constant. Next, at time t ₅ , the vehicle 1 is started again, and after traveling at low speed (time t ₆ ), deceleration of the vehicle 1 is started (time t ₇ ), and electric power is regenerated by the sub-drive motor 20 . will be Thus, while starting and stopping are repeated at a relatively low speed in an urban area, etc., the electric motor driving mode is set, the vehicle 1 functions purely as an electric vehicle (EV), and the engine 12 does not generate torque. .

Further, when the vehicle 1 is started at time t8 in FIG. ₇ , the vehicle 1 is accelerated. Next, at time t9, when the speed of the vehicle ₁ exceeds a predetermined vehicle speed, the main drive motor 16 is driven and the auxiliary drive motor 20 is also driven. As described above, in the electric motor running mode, when the vehicle speed is equal to or higher than the predetermined value and the acceleration is equal to or higher than the predetermined value, electric power is supplied to the main driving motor 16 and the sub-driving motor 20 in order to obtain the necessary power. Vehicle 1 is driven. At this time, power is supplied to the main drive motor 16 from the battery 18 and power is supplied to the auxiliary drive motor 20 from the capacitor 22 . By supplying power from the capacitor 22 in this way, the voltage of the capacitor 22 decreases.

At time t10 in FIG. ₇ , when the vehicle 1 shifts to constant speed running (the operation of the accelerator pedal becomes less than a predetermined amount), the drive by the sub-drive motor 20 is stopped (torque is no longer generated), and the main drive motor 20 is stopped. Vehicle 1 is driven only by motor 16 . As described above, even when the vehicle 1 is traveling at a speed equal to or higher than the predetermined vehicle speed, the vehicle 1 is driven only by the main drive motor 16 unless the vehicle is accelerated by the predetermined amount or more.

Further, due to the driving of the sub-drive motor ₂₀ between time t ₉ and t ₁₀ , the voltage of the capacitor 22 dropped below a predetermined value. Charge the capacitor 22 . That is, the high-voltage DC/DC converter 26a boosts the electric charge accumulated in the battery 18 and charges the capacitor 22 with the electric charge. As a result, the current for driving the main drive motor 16 and the current for charging the capacitor 22 are discharged from the battery 18 during times t ₁₀ to t ₁₁ in FIG. When a large amount of electric power is regenerated by the auxiliary drive motor 20 and the voltage of the capacitor 22 rises above a predetermined value, the control device 24 sends a signal to the high-voltage DC/DC converter 26a to reduce the voltage of the capacitor 22. to charge the battery 18. In this way, the electric power regenerated by the sub-drive motor 20 is consumed by the sub-drive motor 20, or is temporarily stored in the capacitor 22, and then charged to the battery 18 via the high-voltage DC/DC converter 26a. .

At time t11 in FIG. ₇ , when the vehicle 1 decelerates (the brake pedal is operated), both the main drive motor 16 and the sub-drive motor 20 regenerate the kinetic energy of the vehicle 1 as electric power. Electric power regenerated by the main drive motor 16 is stored in the battery 18 , and electric power regenerated by the sub-drive motor 20 is stored in the capacitor 22 . Thus, when the brake pedal is operated at a vehicle speed equal to or higher than a predetermined vehicle speed, both the main drive motor 16 and the sub-drive motor 20 regenerate electric power, and the battery 18 and the capacitor 22 are charged.

Next, at time t12 in FIG. ₇ , the driver operates a switch (not shown) to switch the vehicle 1 from the electric motor running mode to the internal combustion engine running mode, and depresses the accelerator pedal (not shown). . When the vehicle 1 is switched to the internal combustion engine running mode, the supply of fuel to the engine 12 is started and the engine 12 generates torque. That is, in this embodiment, since the output shaft (not shown) of the engine 12 is directly connected to the output shaft (not shown) of the main drive motor 16, the output shaft of the engine 12 is always connected to the main drive motor 16. It rotates with the drive. However, in the electric motor running mode, fuel is not supplied to the engine 12, so the engine 12 does not generate torque. In the internal combustion engine running mode, torque is generated by starting fuel supply. .

Further, immediately after switching from the electric motor running mode to the internal combustion engine running mode, the control device 24 causes the main drive motor 16 to generate torque for starting the engine (time t ₁₂ to t ₁₃ in FIG. 7). This torque for starting the engine causes the vehicle 1 to travel and the engine 12 to generate torque until the engine 12 actually generates torque after the fuel supply to the engine 12 is started. It is generated to suppress the torque unevenness in the front and rear. Further, in the present embodiment, when the number of revolutions of the engine 12 is less than the predetermined number of revolutions at the time of switching to the internal combustion engine running mode, the fuel supply to the engine 12 is not started, and the torque for starting the engine is generated. When 12 reaches a predetermined number of revolutions or more, fuel supply is started. In this embodiment, fuel supply is started when the rotation speed of the engine 12 rises to 2000 rpm or more.

After the engine 12 is started, in the internal combustion engine running mode, the power for driving the vehicle 1 is exclusively output from the engine 12, and the power for driving the vehicle 1 is supplied by the main drive motor 16 and the auxiliary drive motor 20. No output. Therefore, the driver can enjoy driving feeling of the vehicle 1 driven by the internal combustion engine.

Next, at time t14 _in FIG. 7, when the driver operates the brake pedal (not shown), the fuel supply to the engine 12 is stopped and fuel consumption is suppressed. Further, the kinetic energy of the vehicle 1 is regenerated as electrical energy by the main drive motor 16 and the sub-drive motor 20, and charging currents flow through the battery 18 and the capacitor 22, respectively.

During deceleration of the vehicle 1 in the internal combustion engine running mode, the control device 24 drives the sub-drive motor 20 to perform torque adjustment when switching the transmission 15, which is a stepped transmission (during shifting). The torque generated by this torque adjustment momentarily compensates for torque omission, etc., and does not correspond to the torque for driving the vehicle 1 . Details of the torque adjustment will be described later.

On the other hand, at time t15 in FIG. 7, when the vehicle ₁ stops, the controller 24 supplies the minimum amount of fuel necessary to keep the engine 12 idling. The control device 24 also causes the main drive motor 16 to generate assist torque so that the engine 12 can maintain idling at a low rotational speed.

In this embodiment, the engine 12 is a flywheelless engine, but the assist torque generated by the main drive motor 16 acts as a pseudo-flywheel, and the engine 12 maintains smooth idling at low rpm. can be done. Moreover, by adopting a flywheelless engine, high responsiveness of the engine 12 can be obtained during running in the internal combustion engine running mode, and driving with a good feeling can be enjoyed.

Further, when the vehicle 1 is started from a stopped state in the internal combustion engine running mode, the control device 24 sends a signal to the main drive motor 16 to indicate the number of revolutions of the main drive motor 16 (=the number of revolutions of the engine 12). up to a predetermined number of revolutions. After the engine speed rises to a predetermined speed, the control device 24 supplies fuel for driving the engine to the engine 12 to cause the engine 12 to drive, and the vehicle travels in the internal combustion engine travel mode.

Next, with reference to FIGS. 8 to 10, changes in the acceleration of the vehicle 1 when switching the transmission 15 (during shifting) will be described.
FIG. 8 is a graph schematically showing the acceleration of the vehicle 1 when the transmission 15 is switched to the high speed side (shifted up), with the horizontal axis representing time [Sec] and the vertical axis representing acceleration [m/Sec ² ]. is. Similarly, FIGS. 9 and 10 show the acceleration of the vehicle 1 when the transmission 15 is switched to the low speed side (shifted down), with the horizontal axis representing time [Sec] and the vertical axis representing acceleration [m/Sec ² ]. It is a graph schematically shown.

First, FIG. 8 shows changes in acceleration of the vehicle 1 when the transmission 15 is switched from the 1st speed to the 2nd speed with the accelerator pedal (not shown) of the vehicle 1 fully depressed. Here, in the example shown in FIG. 8, the acceleration of the vehicle 1 before shifting is G1 [m/Sec ² ]. First, as shown by the dashed line in FIG. 8, in a so-called auto shift manual (ASM) type general transmission that automatically switches the stepped transmission by an actuator, the gear shift takes about 300 to 800 [mSec] (in FIG. 8). In the example, it takes about 500 [mSec]). During this time, the acceleration of the vehicle decreases to about 0 G, and the occupant feels a "stall" and feels uncomfortable.

On the other hand, as shown by the one-dot chain line in FIG. 8, in an automatic transmission equipped with a torque converter, the drop in acceleration when shifting from 1st to 2nd is extremely small, and the occupant feels a "stall." no.
Furthermore, as shown by the solid line in FIG. 8, in this embodiment, as the transmission 15, a seamless shift type transmission is adopted in which the driving force is not substantially interrupted when shifting to the high speed side. is suppressed. That is, in the present embodiment, the amount of decrease in acceleration during gear shifting is suppressed to α% or less of the acceleration G1 before gear shifting. This drop in acceleration of about α% at the time of gear shifting is sufficient for the performance of a vehicle with sports specifications, and the occupant hardly feels a "stall feeling."

On the other hand, it is conceivable to use the driving force of the motor to suppress the drop in acceleration in a general auto-shift manual transmission shown by the dashed line in FIG. _In this case, in order to suppress the drop in acceleration indicated by the dashed line in FIG. be. The motor torque ΔT ₁ required for this assist is large, and is comparable to the torque required in an electric vehicle that runs on a single motor. lead to an increase.

Next, FIG. 9 shows changes in the acceleration of the vehicle 1 when the transmission 15 is switched from the 3rd speed to the 2nd speed with the accelerator pedal (not shown) of the vehicle 1 being depressed. That is, in FIG. 9, the transmission 15 is switched to the low speed side (shift down) in a state where the accelerator pedal (not shown) of the vehicle 1 is depressed so that the accelerator opening increases at a predetermined speed from a predetermined vehicle speed. is).

Here, in the example shown in FIG. 9, the acceleration of the vehicle 1 before shifting is G2 [m/Sec ² ]. First, as shown by the dashed line in FIG. 9, in a typical auto-shift manual type transmission, it takes about 300 to 1000 [mSec] (about 600 [mSec] in the example of FIG. 9) for shifting. During this time, the acceleration of the vehicle decreases to about 0 G, and the occupant feels a "stall" and feels uncomfortable.

On the other hand, as shown by the one-dot chain line in FIG. 9, in an automatic transmission equipped with a torque converter, the drop in acceleration when shifting from 3rd to 2nd is extremely small, and the occupant feels a "stall". no.
Here, in the present embodiment, a seamless shift type transmission is adopted as the transmission 15, but the driving force is interrupted when shifting to the low speed side (downshifting). Therefore, in the present embodiment, when shifting to the low speed side, the control device 24 sends a signal to each sub-drive motor 20 to generate driving force to compensate for the drop in driving force. That is, as shown by the solid line in FIG. 9, in this embodiment, when the transmission 15 shifts to the low speed side, the auxiliary drive motor 20 is caused to generate a driving force to compensate for the discontinuity of the driving force during shifting. , which prevents acceleration drop. Therefore, sufficient performance is obtained as a sports vehicle, and the occupants do not feel a "stall feeling."

As described above, in this embodiment, the driving force of the sub-drive motor 20 compensates for the drop in acceleration to the same extent as in a general auto-shift manual transmission indicated by the dashed line in FIG. Here, the torque required to suppress the acceleration drop to α% or less relative to the acceleration G2 before shifting is ΔT ₂ [Nm]. This torque ΔT ₂ is sufficiently smaller than the torque required when shifting to the high speed side illustrated in FIG.

Further, in the present embodiment, the discontinuity of the driving force of the main driving wheels (rear wheels 2a) due to downshifting is compensated by the auxiliary driving wheels (front wheels 2b) by the auxiliary driving motor 20, which is an in-wheel motor. Therefore, the driving force can be complemented with high responsiveness without being affected by the dynamic characteristics of the power transmission mechanism 14 that transmits power from the engine 12 to the main drive wheels. Further, the driving force by the auxiliary driving motor 20 when switching the transmission 15 to the low speed side is generated for a very short time and does not substantially drive the vehicle 1 . Therefore, the driving force generated by the sub-driving motor 20 can be generated by electric charges regenerated by the sub-driving motor 20 and accumulated in the capacitor 22 .

Next, FIG. 10 shows the deceleration of the vehicle 1 when the transmission 15 is switched from the 3rd speed to the 2nd speed in a state in which the vehicle 1 is decelerated by engine braking without stepping on the accelerator pedal (not shown). change. In the example shown in FIG. 10, the acceleration of the vehicle 1 before shifting is smaller than 0, and in this state, the transmission 15 shifts to the low speed side. First, as shown by the dashed line in FIG. 10, a general auto-shift manual transmission requires about 300 to 1000 [mSec] (about 600 [mSec] in the example of FIG. 10) for gear shifting. During this time, the deceleration by the engine brake does not work, so the acceleration of the vehicle rises to about 0 G, giving the occupant a feeling of "running idle" and feeling uncomfortable.

On the other hand, as shown by the one-dot chain line in FIG. 10, in an automatic transmission equipped with a torque converter, the increase in acceleration when shifting from 3rd to 2nd gear is extremely small, and the occupant feels "free running". never.
Here, in the present embodiment, a seamless shift type transmission is adopted as the transmission 15, but the engine brake does not act for a predetermined time when shifting to the low speed side (downshifting). For this reason, in the present embodiment, when the vehicle 1 is decelerated and the gear is shifted to the low speed side, the control device 24 sends a signal to each sub-drive motor 20 to regenerate the kinetic energy of the vehicle 1 to generate a braking force. generate That is, as shown by the solid line in FIG. 10, in this embodiment, when the transmission 15 is switched to the low speed side during deceleration, the kinetic energy is regenerated by the sub-drive motor 20, and the braking force is reduced during gear shifting. It compensates for the discontinuity and prevents the increase in acceleration. Therefore, sufficient performance is obtained as a sports vehicle, and the occupants do not feel "free running".

As described above, in the present embodiment, the braking force generated by the regeneration of the sub-drive motor 20 suppresses the increase in acceleration to the same degree as in the general auto-shift manual transmission indicated by the dashed line in FIG. 10 . Here, the braking torque required to obtain a braking force equivalent to that of normal engine braking is ΔT ₃ [Nm]. This braking torque ΔT ₃ can be sufficiently obtained by regeneration of the relatively small sub-drive motor 20, and can effectively suppress the "free running feeling".

According to the vehicle drive system 10 of the first embodiment of the present invention, the control device 24 causes the sub-drive motor 20, which is an assist motor, to generate a drive force to compensate for the discontinuity of the drive force during shifting (FIG. 9). , the "stall feeling" given to the occupant can be suppressed, and the ride comfort of the vehicle can be improved. Further, according to the vehicle drive system 10 of the present embodiment, the seamless shift type transmission 15 (FIG. 6), in which the driving force is not substantially interrupted when shifting to the high speed side, and the driving force when shifting to the low speed side. A relatively small sub-drive motor 20 is combined to compensate for the discontinuity. Therefore, it is possible to improve the ride comfort of the vehicle 1 by suppressing the interruption of the driving force at the time of shifting while avoiding the deterioration of the motion performance due to the large increase in the vehicle weight and the large increase in the cost. .

Further, according to the vehicle drive system 10 of the present embodiment, since the main drive motor 16 that generates the drive force for the rear wheels 2a, which are the main drive wheels, is provided, an electric motor drive mode that does not use the drive force of the engine 12 ( 7) can be realized. As a result, the vehicle 1 can be driven even in areas where the driving of the vehicle 1 by the engine 12 is restricted. Further, when the vehicle 1 is accelerated at a predetermined vehicle speed or higher, the auxiliary drive motor 20 generates driving force (time t ₉ in FIG. 7), so that the small main drive motor 16 can be used to realize the electric motor driving mode. As a result, the weight of the entire vehicle can be reduced.

Furthermore, according to the vehicle drive system 10 of the present embodiment, since the auxiliary drive motor 20 is an in-wheel motor (FIG. 5), the generated driving force is directly transmitted to the wheels, so that the vehicle is driven at the timing when the driving force is interrupted. 1 can be instantaneously applied with a driving force. Therefore, it is possible to more effectively suppress the sense of stall given to the occupant due to the interruption of the driving force.

Further, according to the vehicle drive system 10 of the present embodiment, the auxiliary drive motor 20 is an in-wheel motor, and the front wheels 2b, which are auxiliary drive wheels, are directly driven without changing the output of the motor (Fig. 1) Therefore, there is no need to provide a mechanism for changing the rotation output of the auxiliary drive motor 20, and the weight of the vehicle 1 can be reduced.

Furthermore, according to the vehicle drive system 10 of the present embodiment, the driving force generated by the main drive motor 16 is not generated in the internal combustion engine running mode (FIG. 7), so the vehicle 1 is driven by the driving force generated by the engine 12. , the driver can fully enjoy the driving feeling of the vehicle 1 running on the engine 12 .

Further, according to the vehicle drive system 10 of the present embodiment, the driving force generated by the engine 12 arranged in the front part of the vehicle 1 is transmitted to the rear wheels 2a, and the rear wheels 2a are driven. Exercise performance can be enhanced.

Next, a vehicle drive system according to a second embodiment of the invention will be described with reference to FIG.
FIG. 11 is a layout diagram of a vehicle equipped with a vehicle drive system according to a second embodiment of the invention.

The vehicle drive system according to this embodiment differs from the above-described first embodiment in the transmission structure of the driving force generated by the engine and in the arrangement of the auxiliary drive motor. Therefore, only the portions of the vehicle drive system according to the present embodiment that differ from those of the first embodiment will be described here, and the same components will be denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 8, a vehicle 100 equipped with a vehicle drive system 110 according to the second embodiment of the present invention has an internal combustion engine 112 mounted in front of the driver's seat. Further, the vehicle 100 is a so-called FR (Front Engine Rear Drive) vehicle in which a pair of left and right rear wheels 2a that are main driving wheels are driven by the driving force of the engine 112 . The rear wheels 2a are also driven by a main drive motor 116 and a sub-drive motor 120, as will be described later.

A vehicle drive system 110 according to the second embodiment of the present invention mounted on a vehicle 100 includes an engine 112 that drives the rear wheels 2a, a transmission 115 that is a stepped transmission, and a main drive motor 116 that drives the rear wheels 2a. , a battery 118, and a controller 124, which is a motor controller. Further, the vehicle drive system 110 has a sub-drive motor 120, which is an assist motor for driving the left and right rear wheels 2a, and a capacitor 122 arranged in the vicinity thereof.

Engine 112 is an internal combustion engine for generating driving force for rear wheels 2 a that are main driving wheels of vehicle 100 . In this embodiment, the driving force of the engine 112 arranged in the front part of the vehicle 100 is applied to the left and right rear wheels 2a via the transmission 115, the propeller shaft 117a, the coupling 117b, and the rear differential gear 117c for the rear wheels. is transmitted to

The transmission 115 is a stepped transmission that converts the rotation speed of the output shaft of the engine 112 and outputs the output. transmitted to the wheel 2a. Also in this embodiment, as the transmission 115, a seamless shift type transmission is adopted in which the driving force to be transmitted is interrupted when shifting to the low speed side, but the driving force is not substantially interrupted when shifting to the high speed side. there is Further, the propeller shaft 117a is passed through a tunnel portion formed in the lower center of the vehicle 100 so as to extend in the front-rear direction, and a coupling 117b is connected to the rear end thereof. Coupling 117b transmits the input driving force to rear differential gear 117c.

Main drive motor 116 is an electric motor for generating driving force for the main drive wheels, is provided on the vehicle body of vehicle 100 , and is arranged behind engine 112 and adjacent to engine 112 . Further, an inverter 116 a is arranged in the tunnel portion of the vehicle 100 , and this inverter 116 a converts the DC voltage of the battery 118 into AC voltage and supplies it to the main drive motor 116 . Further, as shown in FIG. 11, the main drive motor 116 is connected in series with the engine 112, and the driving force generated by the main drive motor 116 is also transmitted to the rear wheels 2a via the transmission 115. As shown in FIG. In this embodiment, a 25 kW permanent magnet motor (permanent magnet synchronous motor) driven at 48 V is employed as the main drive motor 116 .

The battery 118 is a capacitor for storing electrical energy that primarily operates the main drive motor 116, and is located behind the inverter 116a in the tunnel section. Furthermore, in this embodiment, a 48 V, 3.5 kWh lithium ion battery (LIB) is used as the battery 118 .

Next, the sub-driving motor 120 is provided so as to generate driving force for the rear wheels 2a, which are the main driving wheels, and is integrated with the coupling 117b and the rear differential gear 117c for the rear wheels. Auxiliary drive motor 120 is an on-board motor provided on the vehicle body side of vehicle 100, and a driving force is transmitted to left and right rear wheels 2a via rear differential gear 117c without transmission 115. Further, as shown in FIG. 11, the current from a capacitor (CAP) 122 is converted into alternating current by an inverter 120a for the sub-driving motor and supplied to the sub-driving motor 120 .

A capacitor 122 is provided to store power regenerated by the sub-drive motor 120 . As shown in FIG. 11, capacitor 122 and inverter 120a are arranged adjacent to coupling 117b, rear differential gear 117c, and sub-drive motor 120, which are arranged in the center of vehicle 100 in the width direction. Also, the capacitor 122 is connected in series with the battery 118, and the power from the capacitor 122 is supplied to the auxiliary drive motor 120 via the inverter 120a and the wire harness 122a.

As a result, the sub-drive motor 120 is driven at a voltage higher than the voltage across the terminals of the battery 118 . Additionally, capacitor 122 is configured to store charge at a higher voltage than battery 118 . A high-voltage DC/DC converter 126a, which is a voltage converter, is connected between the battery 118 and the capacitor 122. FIG. Bidirectional charging between the battery 118 and the capacitor 122 can be performed by the high voltage DC/DC converter 126a. A low-voltage DC/DC converter 126b is connected between the battery 118 and the 12V electrical equipment (not shown) of the vehicle 100, and steps down the electric charge accumulated in the battery 118 to 12V and supplies it to the electrical equipment. can supply.

On the other hand, as shown in FIG. 11, the control device 124 is configured to control the engine 112, the main drive motor 116 and the sub-drive motor 120 to execute the electric motor driving mode and the internal combustion engine driving mode. Further, the control device 124 is configured to cause the sub-drive motor 120 to generate a driving force when the transmission 115 shifts to the low speed side, and compensate for the discontinuity of the driving force during shifting. Specifically, the control device 124 can be composed of a microprocessor, a memory, an interface circuit, and a program (not shown) for operating them.

Since the vehicle drive system 110 according to the second embodiment of the present invention is configured as described above, the driving force generated by the sub-drive motor 120 which is an assist motor is transmitted to the main drive wheels without passing through the transmission 115 . Acts on ring 2a. That is, since the auxiliary drive motor 120 is arranged downstream of the transmission 115 in the power transmission system from the engine 112 , it can drive the rear wheels 2 a without the transmission 115 . For this reason, as in the vehicle drive system 10 according to the first embodiment of the present invention, the drive force generated by the auxiliary drive motor 120 is generated at the time of shifting to the low speed side, thereby complementing the interruption of the drive force by the transmission 115. be able to.

According to the vehicle drive system 110 of the second embodiment of the present invention, the drive force of the auxiliary drive motor 120, which is an assist motor, is used to drive the rear wheels 2a, which are the main drive wheels, to compensate for the interruption of the drive force during gear shifting. can be complemented. That is, in the vehicle drive system 110 of the present embodiment, the driving force of the auxiliary driving motor 120, which is an assist motor, acts on the main driving wheels together with the driving force of the engine 112. FIG. However, since the driving force of the sub-drive motor 120 is applied to the downstream side of the transmission 115 without passing through the transmission 115 , it is possible to compensate for the interruption of the driving force in the transmission 115 .

Although preferred embodiments of the present invention have been described above, various modifications can be made to the above-described embodiments. In particular, in the above-described embodiment, the vehicle drive system of the present invention is applied to an FR vehicle. The present invention can be applied to various types of vehicles such as a so-called RR vehicle in which an engine is arranged in the rear wheels and the rear wheels are the main drive wheels. Further, in the above-described embodiment, a main drive motor for driving the main drive wheels is provided, but the present invention can also be applied to a vehicle drive system that does not include a main drive motor.

In addition, in the above-described first embodiment, the in-wheel motor is employed as the assist motor (sub-driving motor 20) to drive the sub-driving wheels. The present invention can also be configured to compensate for the discontinuity of . Furthermore, in the above-described second embodiment, the on-board motor is employed as the assist motor (sub-drive motor 120) to drive the main drive wheels, but the in-wheel motor drives the main drive wheels to generate driving force. The present invention can also be configured to compensate for the discontinuity of .

1 vehicle 2a rear wheel (main driving wheel)
2b front wheel (secondary drive wheel)
10 vehicle driving device 12 engine (internal combustion engine)
14 power transmission mechanism 14a propeller shaft 14b clutch 15 transmission (stepped transmission)
16 main drive motor (main drive motor)
16a Inverter 18 Battery (accumulator)
20 sub-drive motor (assist motor)
20a inverter 22 capacitor 22a bracket 22b harness 24 control device (motor control device)
26a high voltage DC/DC converter (voltage converter)
26b Low voltage DC/DC converter 28 Stator 28a Stator base 28b Stator shaft 28c Stator coil 30 Rotor 30a Rotor main body 30b Rotor coil 32 Electrical insulating fluid chamber 32a Electrical insulating fluid 34 Bearing 36 Main shaft 38 Countershaft 40 Low speed side gear 40a Gear 40b Gear 40c clutch tooth 42 high speed side gear 42a gear 42b gear 42c clutch tooth 44 dog clutch 46 dog clutch 48 shift fork 48a recess 50 shift fork 50a recess 52 clutch cam ring 52a cam groove 54 clutch ring 54a cam protrusion Part 54b Clutch tooth 56 Clutch cam ring 56a Cam groove 58 Clutch ring 58a Cam protrusion 58b Clutch tooth 100 Vehicle 110 Vehicle drive device 112 Engine 115 Transmission (stepped transmission)
116 Main drive motor 116a Inverter 117a Propeller shaft 117b Coupling 117c Rear differential gear 118 Battery 120 Sub drive motor (assist motor)
120a Inverter 122 Capacitor 122a Wire harness 124 Control device (motor control device)
126a high voltage DC/DC converter 126b low voltage DC/DC converter

Claims (6)

A vehicle drive system for driving a vehicle using an internal combustion engine,
an internal combustion engine that generates driving force for driving main drive wheels of the vehicle;
a stepped transmission connected to the output shaft of the internal combustion engine for converting the rotation speed of the output shaft of the internal combustion engine and outputting the output;
an assist motor provided to apply a driving force to the sub-driving wheels or to apply the driving force to the main driving wheels without going through the stepped transmission;
a motor control device for controlling the driving force output by the assist motor,
The stepped transmission is a seamless shift type transmission in which the driving force to be transmitted is interrupted when shifting to the low speed side, but the driving force is substantially not interrupted when shifting to the high speed side,
A vehicle driving device, wherein the motor control device causes the assist motor to generate a driving force when shifting to a lower speed side by the stepped transmission to compensate for interruption of the driving force during shifting. Further, the vehicle body has a main drive motor that generates driving force for the main drive wheels, and the motor control device uses the drive force generated by the main drive motor and the assist motor. 3. The motor control device is configured to be capable of executing an electric motor running mode for running the vehicle, and wherein the motor control device causes the assist motor to generate a driving force only when the vehicle is accelerated at a predetermined vehicle speed or higher in the electric motor running mode. 1. A vehicle drive system according to claim 1. 3. The vehicle drive system according to claim 1, wherein the assist motor is an in-wheel motor provided on the main drive wheel or the auxiliary drive wheel. 4. The vehicle drive system according to any one of claims 1 to 3, wherein the assist motor is provided so as to directly drive the sub-driving wheels without having its output changed. The motor control device is configured to be capable of executing an internal combustion engine running mode in which the vehicle is driven by the driving force generated by the internal combustion engine. 5. The vehicle drive system according to claim 2, which does not generate driving force. Further, a power transmission mechanism for transmitting the driving force generated by the internal combustion engine is provided, the internal combustion engine is arranged in the front part of the vehicle, and the driving force generated by the internal combustion engine is mainly transmitted by the power transmission mechanism. 6. The vehicle drive system according to any one of claims 1 to 5, wherein the power is transmitted to rear wheels that are driving wheels.

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